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The European Physical Journal Special Topics

, Volume 167, Issue 1, pp 41–46 | Cite as

X-ray diffraction study of the composition and strain fields in buried SiGe islands

  • N. HraudaEmail author
  • J. J. Zhang
  • M. Stoffel
  • J. Stangl
  • G. Bauer
  • A. Rehman-Khan
  • V. Holý
  • O. G. Schmidt
  • V. Jovanovic
  • L. K. Nanver
Regular Article

Abstract

We report on studies of strain and composition of two-dimensionally ordered SiGe islands grown by molecular beam epitaxy using high resolution x-ray diffraction. To ensure a small size distribution of the islands, pit-patterned \(4''\) (001) Si wafers were used as substrates. The Si wafers were patterned by optical lithography and reactive ion etching. The pits for island growth are ordered in regular 2D arrays with periods ranging from 500 to 1000 nm along two orthogonal 〈110〉 directions. After the growth of a Si buffer layer, 5 to 9 monolayers of Ge are deposited, leading to the formation of islands with either dome- or barn shape, depending on the number of monolayers deposited. The Si capping of the islands is performed at low temperatures (300C) to avoid intermixing and thus strain relaxation. Information on the surface morphology obtained by atomic force microscopy (AFM) was used to set up models for three-dimensional Finite Element Method (FEM) simulations of the islands including the patterned Si substrate. In the model, special attention was given to the non uniform distribution of the Ge content within the islands. The FEM results served as an input for calculating the diffracted x-ray intensities using kinematical scattering theory. Reciprocal space maps around the vicinity of symmetric (004) and asymmetric (113) and (224) Bragg peaks were recorded in coplanar geometry. Simulating different germanium gradients leads to altered scattered intensity distribution and consequently information on this quantity is obtained for both dome- and barn-shaped islands as well as on the strain fields.

Keywords

European Physical Journal Special Topic Finite Element Method Model Finite Element Method Simulation Atomic Force Microscopy Data Finite Element Method Result 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© EDP Sciences and Springer 2009

Authors and Affiliations

  • N. Hrauda
    • 1
    Email author
  • J. J. Zhang
    • 1
  • M. Stoffel
    • 2
  • J. Stangl
    • 1
  • G. Bauer
    • 1
  • A. Rehman-Khan
    • 1
  • V. Holý
    • 3
  • O. G. Schmidt
    • 2
  • V. Jovanovic
    • 4
  • L. K. Nanver
    • 4
  1. 1.Institute for Solid State and Semiconductor Physics, Johannes Kepler University of LinzLinzAustria
  2. 2.IWF Dresden, Helmholtzstrasse 20DresdenGermany
  3. 3.Faculty of Mathematics and Physics, Charles University PraguePrahaCzech Republic
  4. 4.TU Delft, Stevinweg 1, 2628DelftThe Netherlands

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